Undercut feature recognition in automatic mold design requires analyzing the visibility/accessibility of the part along a known parting direction, the existing approaches for which are mostly restricted to polyhedral parts or a particular CAD platform or cannot handle partially accessible faces very well. The present work proposes a projection-based methodology to analyze the visibility of a part from a given parting direction without discretizing the part. An approach to further extract undercut features and generate corresponding side-cores is also presented. The implemented system uses STEP AP214/AP203 part files for input and output and has been successfully validated using parts geometrically similar to those used in literature as well as on a number of industrial parts of greater complexity. © 2012 World Scientific Publishing Company.